# 17 20 20 triangle

### Acute isosceles triangle.

Sides: a = 17   b = 20   c = 20

Area: T = 153.8832869417
Perimeter: p = 57
Semiperimeter: s = 28.5

Angle ∠ A = α = 50.30113268251° = 50°18'5″ = 0.87879237712 rad
Angle ∠ B = β = 64.84993365875° = 64°50'58″ = 1.13218344412 rad
Angle ∠ C = γ = 64.84993365875° = 64°50'58″ = 1.13218344412 rad

Height: ha = 18.10438669902
Height: hb = 15.38882869417
Height: hc = 15.38882869417

Median: ma = 18.10438669902
Median: mb = 15.63664957711
Median: mc = 15.63664957711

Inradius: r = 5.39993989269
Circumradius: R = 11.04773635333

Vertex coordinates: A[20; 0] B[0; 0] C[7.225; 15.38882869417]
Centroid: CG[9.075; 5.12994289806]
Coordinates of the circumscribed circle: U[10; 4.69551295017]
Coordinates of the inscribed circle: I[8.5; 5.39993989269]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 129.6998673175° = 129°41'55″ = 0.87879237712 rad
∠ B' = β' = 115.1510663413° = 115°9'2″ = 1.13218344412 rad
∠ C' = γ' = 115.1510663413° = 115°9'2″ = 1.13218344412 rad

# How did we calculate this triangle?

Now we know the lengths of all three sides of the triangle and the triangle is uniquely determined. Next we calculate another its characteristics - same procedure as calculation of the triangle from the known three sides SSS. ### 1. The triangle circumference is the sum of the lengths of its three sides ### 2. Semiperimeter of the triangle ### 3. The triangle area using Heron's formula ### 4. Calculate the heights of the triangle from its area. ### 5. Calculation of the inner angles of the triangle using a Law of Cosines ### 6. Inradius ### 7. Circumradius ### 8. Calculation of medians #### Look also our friend's collection of math examples and problems:

See more informations about triangles or more information about solving triangles.